Service interruption minimizing system for power distribution line

Abstract

Upon the occurrence of a fault on the first distribution line, a faulty section on the distribution line is pinpointed, then a tie point switchgear at the tie point between the first distribution line in which the fault occurred and the other normal second distribution line is closed to form a loop distribution system. Then, a switchgear adjacent to the fault point on the first distribution line is opened. An opposing switchgear adjacent to the fault point is opened on the condition that the fault occurrence continues after having been linked to the second distribution line. The above procedures are executed before the opening of the circuit breaker installed on the distribution bus bar.

What is claimed is: 
     
       1. A service interruption minimization system for a power distribution line, comprising: first and second distribution lines each respectively connected to first and second bus bars via first and second circuit breakers, respectively, and having switchgears disposed at appropriate sites thereof, one of said switchgears serving as a tie point switchgear disposed between end portions of said first and said second distribution lines, the tie point switchgear being in an open state normally;   a protective relay for opening said first circuit breaker upon elapse of a preset time after occurrence of a fault on the first distribution line;   closing means for closing said tie point switchgear upon occurrence of a fault defining a load side of the fault and a bus bar side of the fault on said first distribution line;   first opening means for opening a first switchgear which is adjacent to said fault point and located on the bus bar side of said fault point after closing of said tie point switchgear by said closing means; and   second opening means for opening a second switchgear which is adjacent to said fault point and located on the load side of said fault point, the opening of said second switchgear being executed on the condition that the fault still remains after the opening of said first switchgear;   wherein said second switchgear is effected to open within a preset period of time preset for said protective relay to start its operation.   
     
     
       2. A service interruption minimization system for a power distribution line, comprising: first and second distribution lines each respectively connected to first and second bus bars via first and second circuit breakers, respectively, and having switchgears disposed at appropriate sites thereof, one of said switchgears serving as a tie point switchgear disposed between the end portions of said first and said second distribution lines, the tie point switchgear being in an open state normally;   a protective relay for opening the first circuit breaker upon elapse of a preset time after the occurrence of a fault on the first distribution line; and   a master station connected to said switchgears via a communication line;   wherein said master station transmits a closing instruction to close said tie point switchgear upon the occurrence of a fault on the first distribution line, pinpoints a fault point defining a load side and a bus bar side of the fault point to impart an open instruction to open a first switchgear adjacent to the fault point and on the bus bar side of the fault point, then permits for a second switchgear to open which is adjacent to said fault point and on the load side of the fault point, wherein all these series of operations from fault occurrence to the opening of the second switchgear are carried out within a preset period of time preset for said protective relay to start its operation.   
     
     
       3. A service interruption minimization system for a power distribution line according to claim 2, wherein each switchgear includes a fault detection function, and transmits a fault detection signal via said communication line, and wherein the master station pinpoints the fault point in dependence on a fault detection signal transmitted from the switchgear which has detected the fault. 
     
     
       4. A service interruption minimization system for a power distribution line according to claim 2, wherein each switchgear includes a fault detection function, a transmission function for transmitting a fault detection signal via said communication line, and a function to open one of the switchgears when it receives no fault detection signal from the load side of the fault point or in response to an instruction from the master station. 
     
     
       5. An operating method for operating power distribution lines comprising the steps of: supplying a first distribution line from a first bus bar, and a second distribution line from a second bus bar under normal operating conditions;   shifting a power supply state when a fault occurs in the first distribution line to such where both distribution lines are supplied both from the first and the second bus bars; and   subsequently shifting to another supply state where a portion of the first distribution line without inclusion of the fault point is supplied from the first bus bar, and the remaining portions of the first distribution line and the second distribution line are supplied from the second bus bar.   
     
     
       6. An operating method for operating power distribution lines comprising the steps of: supplying a first distribution line from a first bus bar, and a second distribution line from a second bus bar under normal operating conditions;   shifting a power supply state when a fault occurs in the first distribution line to such where both distribution lines are supplied both from the first and the second bus bars; and subsequently, shifting to another supply state where a portion of the first distribution line without inclusion of the fault point is supplied from the first bus bar, and the remaining portions of the first distribution line and the second distribution line are supplied from the second bus bar; and   removing the fault point from power supply sections to be supplied from the second bus bar.